Added basic implementation for Python code evaluation

evaluators/BaseEvaluator.py

@@ -0,0 +1,14 @@
+class BaseEvaluator:
+    """
+    base class to evaluate concepts or nodes
+    """
+
+    def __init__(self, name, priority: int):
+        self.name = name
+        self.priority = priority
+
+    def matches(self, context, items):
+        pass
+
+    def eval(self, context, items):
+        pass